Thanks for the book link. No chance of finding it in my book store.

The "windows" are symmetrical. The radius is 12 7/8. The "windows" make
up a the top half of the circle. Using a protractor I figure the top
angle is 74 degrees and the bottom angle is 85 degrees. I managed to
get the wood bent (steamed) and cut but it is not a nice tight job. I
would have liked to have done it better.

Thanks for the advice.